Optical conductivity of wet DNA

TL;DR

This study uses density functional theory to analyze how water molecules and structural defects influence the optical conductivity of DNA in its natural, aqueous environment, revealing thermally activated doping effects.

Contribution

It introduces a detailed computational approach to understand water-induced doping and its impact on DNA's optical properties, highlighting the role of structural defects.

Findings

Water near DNA ends, breaks, or nicks causes doping effects

Water molecules lead to low-frequency absorption in DNA

Doping is thermally activated and structurally dependent

Abstract

Motivated by recent experiments we have studied the optical conductivity of DNA in its natural environment containing water molecules and counter ions. Our density functional theory calculations (using SIESTA) for four base pair B-DNA with order 250 surrounding water molecules suggest a thermally activated doping of the DNA by water states which generically leads to an electronic contribution to low-frequency absorption. The main contributions to the doping result from water near DNA ends, breaks, or nicks and are thus potentially associated with temporal or structural defects in the DNA.